The pathogenic bacteria Chlamydiae are responsible for several diseases of public health importance, including pelvic inflammatory disease, female infertility, blindness, arthritis and possibly cancer, asthma, and coronary heart disease. The development of the Chlamydia-related sequelae is postulated to occur via several distinct mechanisms, of which a key element is bacterial inhibition of host cell apoptosis. It has been proposed that Chlamydiae produce bacterial factors that specifically inhibit host cell apoptosis. This application seeks to identify and functionally characterize chlamydial proteins implicated in the inhibition of host cell apoptosis and explore its role in evasion of host specific immune responses. This application will seek to: Identify the chlamydial anti-apoptosis gene product(s). Biologically and biochemically characterize the chlamydial anti-apoptosis gene product. Elucidate the role played by the anti-apoptosis factor in evasion of a specific CD8+ T cell lytic response by heterologous expression in Listeria monocytogenes. The ultimate goal is to better understand how microbial pathogens can manipulate host cell vital processes. [unreadable] [unreadable]